Oh yes, that is cool. I see from the code now (was reading it incorrectly).
So a Quorum with NTS would give me 3 copies across the cluster, not necessarily 2 local and 1 remote, but for most parts that would be true since WAN adds to latency.
CL.QUORUM is supported with any replication strategy, not just simple.
Also, Cassandra's optimizing of cross-DC writes only requires that it
know (via a correctly configured Snitch) where each node is located.
It is not affected by replication strategy choice.
On Thu, Sep 8, 2011 at 3:14 PM, Anand Somani <email@example.com> wrote:
> Have a requirement, where data is spread across multiple DC for disaster
> recovery. So I would use the NTS, that is clear, but I have some questions
> with this scenario
> I have 2 Data Centers
> RF - 2 (active DC) , 2 (passive DC)
> with NTS - Consistency level options are - LOCAL_QUORUM and EACH _QUORUM
> I want LOCAL_QUORUM and 1 remote copy (not 2) for write to succeed, if I
> used EACH_QUORUM - it would mean that I need both the remote nodes up (as I
> understand from http://www.datastax.com/docs/0.8/operations/datacenter).
> So if that is my requirement what consistency Level should I be using for my
> writes? Is that even possible with NTS or another strategy? I could use the
> SimpleStrategy with Quorum, but that would mean sending 2 copies (instead of
> 1 per DC that NTS uses to optimize on WAN traffic) to remote DC (since it
> does not understand DC's)?
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support